Collotype printing form and process of producing the same



Nov. 30', 1926. 1,609,091 1 A. .MILLER COLLOTYPE PRINTING FORM ANDPROCESS OF PRODUCING THE SAME Filed August 14. 1924 Me mar/m1 uw parfPatented Nov, 30, 1926.

UNITED STATES PATENT OFFICE.

ALFRED MILLER, 01 DESSAU IN ANHALT, GERMANY, ASSIGNOR TO I.

- INDUSTRIE AKTIENGESELLSCHAFT, E FRANKFORT-ON-THE-MAIN, GERMANY GOLLOTYP E PRINTING FORM AND PROCESS OF PRODlZTEJING -'JIIBIE SAME.

Application filed August 14, 1924, Serial No. 732,119, and iii Germanynercu aa 1924.

' Phototypy has been performed in the following manner: I

A glass-plate prepared in a sultable manner receives an alqueoussolutionof gelatme 5 and alkali-bichromate and is dried in an oven at a hightemperature. In this man- .ner' there is formed a certain wrinkling ofthe gelatine over the whole plate; this 1s the so-called phototypicgrain (compare A1- 10 bert, Lichtdruck, 1906', page 32). The dried plateis then exposed under anegative and afterwards thoroughly washed anddried,

whereupon it is moistened .as usual with water containing glycerineorthe like and the printing operation may begin. This process has thedisadvantage that the printer is obliged to prepare the materialhimself.

The said disadvantage is overcome-by other processes already proposed byWl'llCll firstly on the support (plates or films) a hardened'gelatinelayer is applied and dried.

Such plates can .be manufactured in large quantities and delivered" tothe printers. They are sensitized directly before use in a 2'5bichromate solution, dried at ordinary temperature or in. a yveaklywarmed current of air. then exposed to light under a negative,

. washed in water at ordinary temperature,

dried and treated with glycerine containing water. Such a-printing formcontrary to the old 'phototypic plate totally grain less, as well in thelights as in the shadows. Pictures produced from them when comparediwiththe impr'css'ionsobtained by the old phototypic process havethedisadvantags that they show an essentially steeper gradation and thehalf-tones, particularly on large surfaces have a certain hard and coldappearance which is not to be observed in theold phototypic process.

Therefore, attempts were made, to give a.

grain to plates manufactured inthe just described manner and exposed tolight under a negative by. acting with chemicals,

such as formaldehyde in connection with acids, on the gelatine layer.This process could not be readily introduced into practice. as theformation of a good grain de-.

from a colloid layer which may be spread .upon a suitablyprepared'support, such as duced. After a glass plate, a brass plate or a .film.The colloid layer if) desired may contain a fine G. FARBEN- I grainedmaterial such as barium sulfate which renders the colloid slightlyopaque when wet and thereby'afl'ords a better sur veying of the inking,operation of the finished printing form. It should be understood,however, that this feature does in no wise affect the forming of thegrain hereinafter described; The layer, is sensitized in the usualbichromate bath. If .as colloid unhardened gelatine' be takenthe layeris dried at a moderately raisedtemperature of about 30 0., whereby nograin is prothe layerhas been exposed under a negative it is washed inmoderately dried. i If a more or less hardened -colloid, for example ahardened gelatine is employed,

with bichromate'solution is dried at a raised temperature. higher. thanthat employed for .unhardened ,gelatine, that is the temperature must bethe higher the greater the degree of warm water, for instance at 2025(3., and V thelayer-whichhas undergone thetreatment hardness of thecolloid. The drying tem- T peratures are relatively low,however, andshould not exceed approximately 35 C. Similarly the temperature of thewashing water preferably is raised in proportion to the degree ofhardness of the colloid.

4 There is thus formed in the exposed places in proportion to the degreeof action of'the light Which produces insolubility of the gelatine amore or less pronounced grain. Thus in contradistinction to the oldphototypic plates which have a grain over thewhole surface, th'e'platesproduced by the new process are grained only in the exposed places,while those parts which have been completely protected from'light arewithout grain. Under a magnifying glass the grain" is seen to haveextra-ordinary closeness and uniformity, whereas the ordinary phototypicgrain frequently has clefts in it and is irregular. The printing formsprepared accordingtothe present invention are distinguished from thoseproduced by any prior method by the fact that, due to the lowdrying'temperatures applied, the areas which have notbeenaflected byexposure to light, i. e., in the high lights and espec'ially the whitemargin surrounding thepicture area, are entirely without grain. By thislack of grain in the areas, which, in

the final print, shall appear entirely colorless, there is avoided thetroublesome ml;- ing of those areas; which latter is expenenced inusing. those printin forms which have an over-all grained sur ace.

The printing forms manufactured by the new process give excellent andjust as well graded prints as the old phototypy and are devoid of theaforesaid disadvan tages of the other processes. Instead of hard andcold pictures the forms produce soft and warm pictures. The advantagesof the. processes mentioned above are united in the new process.

For the sake of illustration reference is made to the accompanyingdrawings in whichr Fig. 1' is a sectional view showing asupport 1carrying a colloid layer 2 before treatment according to the invention;

Fig. 2 is a similar sectional view showing a phototypic printing formprepared by treating the colloid layer 2 in accordance ing itin warmwater. I

printing forms,'which consists in sensitizing by means of afchromieacidsalt a colloid surface, drying the sensitized surface at a temperatureof 28 C. to 35 C. depending upon the degree of hardness of the colloid,exposing it under a negative and then wash- 2. -A process according toclaim 1, wherein the colloid is gelatine.

3. Aprocess according to claim 1, wherein the colloid surface hasembedded in itfa finely grained material. 7

4. A process according to claim 1, wherein the colloid surface hasembedded in it finely divided barium sulphate.

5. In a process ,of producing 'phototypic printing forms from a colloid,the steps .the degree of hardness of the colloid, ex-

posing the thus prepared surface and then washing" the exposed surfacewith water having a temperature -of about 20 C. to

7. In a process of producing phototypi'e printing forms from a colloid,the steps which consist in sensitizirig'th'ecolloid surface by means ofa chromic acid salt, drying the sensitized surface at. a temperature notexceeding 35 0., exposing the thus prepared surface and then washing theexposed surface with warm water. j

'- 8. Process according to claim 7, wherein the colloid is gelatine. Q

9. Process accordin tQ' claim 7, wherein the colloidcis hardenedgelatine.

10. A collotype phototypic pfinting form in which all areas defined byexposure to light .aregrained and all areas unaffected by the light arewithout grain.

11. A collotype phototypic printing form in which alljareas defined byexposure to light have a 'grain the quality of which is proportional tothe'light effects defining the printing surface, and all areasunaffected by the light are without grain.

12. A collotype phototypic printing form in which-allareasdefinedby'exposure to light have a grain'proportional indistinctness to the degree of insolubility caused by the light effects,andall areasunafi'ected by the lightare without grain; In testimonywhereof 'Iaflix my signature. I

- ALFRED MILLER.

